Experimental and predictive study of self-compacting concrete containing reclaimed asphalt pavement

This work focuses on the reuse of reclaimed asphalt pavement (RAP) in the production of self-compacting concrete (SCC) for usage in the construction of rigid pavements. The article first describes an experimental study where five SCC mixtures incorporating 0%, 20%, 40%, 60% and 100% volumetric substitutions of natural aggregates by RAP were formulated. Several characterisation tests in the fresh and hardened states were then performed. The results of all performed tests showed that RAP has a slight negative effect on SCC performance in the fresh state. The most significant reduction observed does not exceed 18% for slump-flow and 10% for L-shaped box values when total substitution is applied. Furthermore, the mechanical properties noticeably decrease with an increase in RAP content, with reductions of up to 37% in 28-d compressive strength and 23% in 28-d indirect tensile (IDT) strength observed in the case of full replacement. However, it is possible to formulate SCC mixtures even with 100% RAP substitutions and meet specifications for rigid pavement construction. In addition, modelling of the various mechanical characteristics made it possible to find out the reason behind the reduction in these properties with RAP content. In fact, the thin bitumen film around RAP particles weakens their surface adhesion with the hydrated cement paste. With the intrinsic RAP properties found, the hardened-state characteristics of any other SCC mixture incorporating RAP could be predicted.